This invention relates to low frequency medical treatment apparatuses in which a low frequency current is allowed to flow through the human body to carry out medical treatment, and more particularly to a circuitry for operating the apparatus securely and comfortably.
Known in the art is a low frequency medical treatment apparatus which carries out medical treatment by applying an electrical output of relatively low voltage and low frequency to necessary portions of the human body on the basis of the phenomenon that upon application of electric current to the human body, especially to a muscle, the muscle is vibrated.
In the medical treatment apparatus of this type, many safety measures of securely applying electric current are required. The safety measures are, for instance, to prevent the flow of excessively large current, and to prevent shocks caused by application of a large electric power to the human body. A variety of circuits have been proposed as the safety measures. However, these conventional circuits are still disadvantageous in responsing characteristics and cost.
On the other hand, the medical treatment apparatus of this type is frequently used, and its medical treatment effects are remarkable. Therefore, it should be taken into consideration whether it can be used comfortably. However, in the conventional medical treatment apparatus mentioned above, measures taken to meet such requirements are not always sufficient and satisfactory.